THE PHOTOELECTRIC ERYTHROCYTE COUNT

Transcription

1 THE PHOTOELECTRIC ERYTHROCYTE COUNT II. CLINICAL APPLICATION* LEON L. BLUM, M.D. From the Laboratories of Associated Physicians and Surgeons' Clinic, Union Hospital and St. Anthony's Hospital, Terre Haute, Indiana In a previous paper 1 the basic principles and technic of photoelectric determination of erythrocyte count were discussed and the use of this method recommended. The method was applied in a large variety of clinical conditions under different circumstances and its clinical value demonstrated. It is the purpose of this paper to outline some clinical applications as they arise in various fields of medical practice. ROUTINE DETECTION OF GROSS ERYTHROCYTIC ABNORMALITIES It is the concensus that the routine determination of hemoglobin and red cell count on all new patients whether hospitalized or not is a valuable procedure. However, with the limited technical help in the laboratory this routine is often neglected due to time consuming and tedious task of doing a dependable red blood count on the counting chamber. The photoelectric method enables to perform a routine determination of hemoglobin and erythrocyte count in less than one minute, eliminating the shaking, filling, refilling the counting chamber and the actual counting. If no anemia is present, then the photoelectric reading can be taken as final and no correction of any kind is necessary. If anemia is present and the unstained blood smear reveals many macrocytes or microcytes, then a correction according to the mean corpuscular diameter will be required. The time saved on normal blood counts will permit more attention to the adequate study of anemic states and the performance of many neglected hematologic procedures, such as examination of the wet drop, unstained and stained smear, measurements of the size of the cells, etc. The close correlation of accurate hemacytometric and photoelectric red cell counts in normal cases was reported previously 1. Table 1 gives representative findings in various conditions of the hematopoietic system. DETECTION OF TREND IN ERYTHROCYTE COUNTS In the expanding scope of preventive medicine, in industrial hygiene and other fields the single determination of a blood count is of much less significance as its determination at regular intervals. Only in such a way can we follow a trend in erythro level and detect minor hematologic abnormalities in the subclinical stage. The large margin of error of routine red cell count and marked variations obtained by various persons at the same time deprive the hemacytometric * Read in part before the meeting of Indiana Association of Pathologists in Indianapolis, Indiana, April 28,

2 54 LEON L. BLUM method of any clinical value for the detection of minor erythro variations. The photoelectric method which eliminates all subjective errors is ideal for this purpose. The time factor and saving of glassware deserves a particular consideration in mass testing in industrial work. Many cases of permanent bone marrow damage due to toxic physical or chemical agents (incl. x-rays) could be prevented if recognized early by the detection of downward trend in erythro level. TABLE l CORRELATION OF HEMACYTOMETRIC AND UNCORRECTED PHOTOELECTRIC ERYTHROCYTE COUNTS IN VARIOUS HEMATOLOGIC CONDITIONS NO. GM. PER 100 CC. R.B.C. IN MILL. Hemacytometer Photelometer TYPE OF ANEMIA CLINICAL CONDITION Hypochromic Normal Normal Asymptomatic elliptocytosis Chronic infection Chronic lymphatic leukemia Bleeding peptic ulcer Aplastic anemia Hypoplastic anemia, treated Acute myelogenous leukemia Menorrhagia Chronic genito-urinary tract bleeding Carcinoma and syphilis Peptic ulcer with dietary deficiency Multiple pregnancies Pernicious anemia, untreated Pernicious anemia, in relapse Pernicious anemia, treated Nutritional anemia of pregnancy Acute hemolytic anemia Carcinoma of pancreas with metastasis to liver DETECTION OF HEMOCONCENTEATION IN SHOCK Hemoconcentration is one of the earliest and dependable signs in many cases of subclinical shock, particularly burn shock. It can be demonstrated by increasing hematocrit values over a period of hours. The disadvantage of the hematocrit method is that it requires repeated venipunctures often difficult or undesirable in patients with shock and prolonged centrifugation at each determination. Changes in hemoglobin or erythrocyte level can also be utilized

3 PHOTOELECTRIC RED CELL COUNT 55 for detection of hemoconcentration. It seems that an erythro curve is a better indicator of impending or existing shock. If serial erythrocyte counts performed about every two hours show a definite upward trend, this indicates progressing hemoconcentration. In my experience the differences between successive counts are frequently of minor degree and may well be within the range of experimental error. The possible range of error at a level of 5 million is far too insufficiently recognized by clinicians and even pathologists and misleading conclusions are often based on variations of 200, ,000. The counting chamber method of erythrocyte enumeration, as it is routinely done in hospital laboratories, is therefore too much subject to errors to be suitable as a method for detection of minor degrees of hemoconcentration. The photoelectric method, on the other hand, is again ideal for this purpose. The subjective errors are eliminated and the readings can be conveniently made in less than one minute. With proper calibration and attention to technic as outlined in the previous communication 1 the erythrocyte count can be determined reliably within 100,000. A convenient method to detect hemoconcentration photoelectrically is to perform serial erythrocyte counts with the same technic every two hours. An increase of 200,000 or more at the successive counts is evidence of progressive hemoconcentration. An increase of from 100,000 to 200,000 should be interpreted with caution. Thus, the photoelectric method offers a simple and dependable means to detect hemoconcentration when ever it occurs in impending shock. EVALUATION OP TREATMENT OF ANEMIAS Photoelectric red cell counts may show a significant difference from hemacytometric counts in cases of anemia with macrocytosis or marked microcytosis, unless correction is made for the mean corpuscular diameter and mean corpuscular hemoglobin concentration. Is the correction clinically essential or desirable? If, e.g. 4 million of small erythrocytes of micro anemia perform the function of 3.5 million, does not the lower photoelectric count give a better picture of the functional status of erythrocytes? Should we not try to supplement the purely morphologic aspects with functional concepts? Indeed, such a viewpoint is valid and deserves serious consideration. But it happens that the size of the red blood cell is a fairly good indicator of the functional activity of the bone marrow and if we ignore it we deprive ourselves of many helpful clues existing in the morphologic classification of anemias. Thus, if a diagnostic hematologic examination reveals the presence of marked anemia and the photoelectric value for red cell count is taken without correction or correlation with the hemacytometric value, then the presence of macrocytosis or microcytosis may be easily overlooked and the anemia masked as normo. Two illustrative examples are given in table 2. These findings demonstrate that for a morphologic classification of an anemia the red cell count must be determined either as a photoelectric count corrected for cell size or as an accurate hemacytometric count. A close agreement between a photoelectric and accurate

4 56 LEON L. BLUM hemacytometric count in case of anemia suggests that the anemia is of normo type. In the follow up of cases of anemia under treatment the photoelectric method may reveal information not available with the counting chamber method. In macro anemias (pernicious anemia type) treated with liver extract, the rise of photoelectric red cell count is slower than that observed with the counting chamber under identical conditions. The reason for it is that erythrocytes of macro anemia under treatment with liver extract become smaller, macro- TABLE 2 DIVERGENCE IN HEMACYTOMETRIC AND UNCORRECTED PHOTOELECTRIC FINDINGS IN TWO CASES OF MARKED ANEMIA TYPE OF ANEMIA HB. IN GM. R.B.C. IN MILL. HEMA TOCRIT VALUE IN CC. M.C. M.C.V. COLOR INDEX VOLUME INDEX Micro M.C. Mean Corpuscular Hemoglobin (in micromiorograms). M.C.V. Mean Corpuscular Volume (in cubic microns). Hemacytometer (counting chamber). Photelometer. TABLE 3 TYPICAL RESPONSE OF MACROCYTIC ANEMIA UNDER TREATMENT AS MEASURED HEMACYTOMETRICALLY AND PHOTOELECTRIC ALLY DATE HB. IN GM. R.B.C. IN MILL. INCREASE IN R.B.C. DIFFERENCE BE TWEEN AND IN MILL Initial count before treatment +990, , , , , , Hemacytometer (counting chamber). Photelometer. cytosis less marked leading to a decreased effective surface of erythrocyte suspensions and thus to lower photoelectric reading. Therefore, a photoelectric increase in red cell count at the start of treatment is more significant as an index of adequate response to treatment (table 3). INTERPRETATION OF BORDERLINE ANEMIC STATES One often encounters in practice cases of borderline anemias which do not fit into any definite group. In determining various hematologic data and indexes, an error in the number of erythrocytes as it may easily occur with the counting chamber method may wrongly place the anemia into macro or micro group. In such cases a photoelectric count will be often helpful.

5 PHOTOELECTRIC RED CELL COUNT 57 If the uncorrected photoelectric count is higher (more than 200,000) than the counting chamber count, then macrocytosis is probably present, whereas in case of microcytosis, the photoelectric count will be found lower (see table 1). The simultaneous determination of the erythrocyte count with the counting chamber and the photelometer may give a clue as to the type of anemia when more detailed hematologic studies including hematocrit are not feasible. Thus, the difference between the uncorrected photoelectric and hemacytometric counts may possess some clinical value. In my experience this clue was helpful in a number of ambulatory patients with various degrees of anemia. FOLLOW UP OF CASES OF ERYTHROCYTOSIS The large range of possible error of routine erythrocyte count at a higher level makes the count highly inaccurate in cases of marked erythrocytosis, such as occurs e.g. in polycythemia vera. At the level of 10 million the possible error is ±1,600,000! Thus, a drop of the count of over 1,000,000 may be within experimental error and not due to the effect of therapeutic agent employed. In view of the recently improved methods for treatment, such as injection of radioactive phosphorus, it is desirable to have a more accurate method for the evaluation of the changes in erythrocyte level. The photoelectric method is particularly suitable for this purpose. In three personally studied cases of polycythemia vera treated with venesection, x-ray, and radioactive phosphorus, I could not detect any significant changes in cell size that could affect photoelectric readings. CONCLUSIONS The possibility of accurate and rapid determination of red cell counts by means of a photoelectric filter photometer constitutes a distinct progress in hematologic technic. The method was tested in a large series of routine and special hematologic examinations and proved superior to the customarily employed counting chamber method. The range of error of routine counting chamber count is far too little realized and leads to many misleading clinical conclusions. The main interference with the reliability of photoelectric results lies in the presence of pronounced macrocytosis or microcytosis easily detectable by the examination of a wet drop or stained blood smear. In such cases a correction of the photoelectric reading according to the mean corpuscular diameter is required. The most suitable procedure for such a correction can be established by further experience and a few minor imperfections of this new method can be readily eliminated. With further improvement in photoelectric apparatus and technic it is hoped that the photoelectric method will replace the hemacytometric method of erythrocyte counting. The saving of time and glassware is particularly important in mass testing and industrial work. Some clinical applications of the photoelectric method and the results obtained are briefly outlined in this paper. REFERENCES 1. BLUM, LEON L.: The photoelectric determination of erythrocyte count. I. Basic principles and technic. Am. J. Clin. Path. (Techn. Bull.) 15: (Nov.) 1945.